1. Field of the Invention
The present invention relates to a hay making machine, particularly a windrower for plant matter lying on the ground, comprising a structure carrying at least one raking wheel which is connected to the end of a carrying arm in such a way as to be able to pivot about a first axis and a second axis which form angles of about 90xc2x0 with one another, which raking wheel is equipped with arms with working tools and can be driven in rotation about an approximately vertical support axis which is equipped at its lower end with support wheels.
2. Discussion of the Background
In known machines of this kind, the first axis of articulation between the raking wheel and its carrying arm is directed in the direction of forward travel and the second articulation axis is perpendicular to the direction of forward travel.
These articulation axes allow the raking wheel to pivot with respect to the carrying arm to follow the unevennesses of the ground during work. The quality of the raking is thus considerably improved.
For transport, the raking wheel is lifted up using the carrying arm through an angle of about 90xc2x0. In this position it is approximately vertical, which makes it possible to reduce the width of the entity and bring it inside the maximum width permissible for road transport. In this position, it is, however, necessary to immobilize the raking wheel so that it can no longer pivot about said articulation axes, particularly about the second axis which is then approximately vertical, during travel along paths or roads. As a result of such pivotings, the tools of the raking wheel could extend beyond the maximum permitted width and present a risk of catching on objects or people possibly located nearby.
These locking means increase the price of the machine. In addition, if they are mounted or removed manually by the user, the user may forget to carry out this operation.
An object of the present invention is to overcome the aforementioned drawbacks of the known machines. The present invention must, in particular, make it possible to obtain, in a very simple way and for a very low cost, automatic immobilization of the raking wheel during transport.
To this end, one important feature of the invention consists in the fact that the two axes of articulation between the raking wheel and the carrying arm form angles with the direction of forward travel of the machine, the values of which are between about 10xc2x0 and 80xc2x0. It is important that neither of these axes forms a right angle with said direction of forward travel. Said angles may advantageously have the same value, namely 45xc2x0.
By virtue of this position of the two articulation axes, the raking wheel is automatically immobilized under the effect of its own weight when raised into the transport position. As a result of this, it is no longer necessary for the machine to be fitted with a device for locking the raking wheel or with means for operating such a device upon each switch from the work position to the transport position and vice versa. The risk of the immobilizing of the raking wheel being forgotten is also eliminated.
According to other features of the invention, the raking wheel is articulated to the first axis by means of two cramps which allow it to pivot about said first axis. The second axis is articulated in cramps of the carrying structure so as to be able to pivot with respect to said structure. The first axis is guided at least at one of its ends in an oblong orifice made in a tab of the carrying structure. The second axis is guided at least at one of its ends in an oblong orifice provided in a tab of the raking wheel. These oblong orifices in a simple way limit the angles of pivoting of the raking wheel about the two articulation axes so as to avoid excessive movements which could be harmful to the quality of the raking work and give rise to damages.